1. Field of the Invention
The present invention relates to an image forming system.
2. Description of the Related Art
There is a tandem-type image forming system, in which image forming apparatuses are connected in series with their sheet conveying paths being connected to one another.
For example, a tandem continuous paper printer is disclosed in Japanese Patent Application Laid-Open Publication No. 2007-8143, the tandem continuous paper printer which is equipped with a first printer, a second printer, and a printer controller, wherein the printer controller outputs the data to be printed by the first printer to the first printer and outputs the data to be printed by the second printer to the second printer.
Moreover, a printer system is disclosed in Japanese Patent Application Laid-Open Publication No. 2009-66937, the printer system which is equipped with a first printer on which a printer controller is mounted, and a second printer on which a printer controller is mounted, wherein when the printer controller mounted on the first printer receives printing data from a host, the printer controller transmits the printing data to the printer controller mounted on the second printer while saving the printing data, and each of the printer controllers processes the printing data.
However, in the tandem continuous paper printer disclosed in Japanese Patent Application Laid-Open Publication No. 2007-8143, when the printer controller assigns image data to each of the image forming apparatuses, it is necessary to check whether the image forming apparatuses finish writing preparation to form image data on a sheet, and adjust timing to convey a sheet therebetween.
Moreover, the writing preparation of the image data of the image forming apparatus provided on the downstream side in a sheet conveying direction must be completed by the stage of the arrival of the sheet conveyed from the image forming apparatus provided on the upstream side. However, if the transfer of the image data between the image forming apparatuses is executed through a communication network, such as Ethernet (registered trademark), the transfer time thereof sometimes varies depending on the congestion state of the communication network, as disclosed in Japanese Patent Application Laid-Open Publication No. 2009-66937.
Consequently, in such conventional technologies, mechanisms are required, the mechanism for temporarily halting a sheet on one side of which an image is formed by the image forming apparatus on the upstream side before conveying the sheet into the image forming apparatus on the downstream side, and the mechanism for ascertaining whether the writing preparation of image data used to form images on both sides of a sheet is completed or not in the image forming apparatus on the upstream side and the image forming apparatus on the downstream side and for adjusting the conveying timing of the sheet. Accordingly, a problem arises that the productivity lowers owing to the operations of these mechanisms.